The entire contents of Japanese Patent Application No. 9-134903 filed on May 26, 1997 and Japanese Patent Application No. 9-147846 filed on Jun. 5, 1997 are incorporated herein by reference.
The present invention relates to an image processing apparatus and method in which the moving picture data encoded by compressing moving pictures using the interframe prediction are sent out and reproduced at a fixed rate, and more particularly to an image processing apparatus and method for realizing what is called a trick play such as rapid feed and reverse rapid feed.
The current mainstream of the technique for encoding moving pictures by a compression scheme using the interframe prediction includes the MPEG2 (Moving Picture Experts Group) international standards. Normally, in a moving picture processing system with MPEG2, as shown in FIG. 1, the moving picture data recorded in a video tape 1 or the like or the real-time moving picture data obtained by use of a video camera 3 or the like are encoded by a dedicated encoder system 5 and stored in an external memory as a moving picture file 7. The moving picture file 7 thus stored is decoded by a dedicated decoder system 9 and reproduced for display on a TV 11 or the like. In this case, there are two techniques for sending the data from the moving picture file 7 to the decoder system 9, a fixed rate and a variable rate. The following two conventional methods are used for realizing the trick play (rapid feed, reverse rapid feed, etc.) with a MPEG2 system.
In the first method, the moving picture data for trick play is prepared in tape or the like beforehand and encoded by an encoder to produce a MPEG2 trick play moving picture file. This method, however, poses the problem that considerable labor and time are required to produce the moving picture data for trick play in advance and to encode it to MPEG2 image data.
In the second method, a moving picture file for ordinary reproduction which is encoded by a MPEG2 encoder is used for trick play reproduction at the time of decoding. As shown in FIG. 2, for example, when decoding the moving picture file 13 for ordinary play, only the intraframe coded pictures (I-pictures) or only the intraframe coded picture and the interframe forward predictive pictures (P-pictures) are decoded out of the frame information sent out to a MPEG2 decoder system 15 and displayed on a TV 17 for realizing the rapid feed.
For realizing a normal rapid feed when data are sent out at a fixed rate by this method, however, a complex process is required for image data search and buffer management at the time of decoding. Also, some decoders based on MPEG2 currently in use have no such a special function and therefore this method is not usable in all cases.